Three US troops have been killed and 25 injured in a drone attack on a US base in Jordan, near the Syria border, the US has announced. US President Joe Biden said the attack was carried out by Iran-backed militant groups operating in Syria and Iraq. "Today, America"s heart is heavy", Biden said, adding "their ultimate sacrifice will never be forgotten by our nation" It is the first time US soldiers have been killed by strikes in the region after Hamas" Oct. 7 attack on Israel. The attack was on Tower 22, in north-east Jordan It has sparked fears of an escalation in the conflict in the region. He also warned of reprisals, adding: "And have no doubt — we will hold all those responsible to account at a time and in a manner our choosing." In its latest statement, Jordan has condemned the targeting of US personnel near its border with Syria, calling it a "terrorist attack", according to a report by Reuters. The country added it was cooperating with the US to secure the border and to fight terrorism. US troops in the Middle East have been attacked dozens of time by Iran-aligned fighters since the war in Gaza started in October, reigniting tensions across the region. The US and UK have also carried out strikes on Yemen"s Iran-backed Houthi movement in response to its missile and drone attacks on international shipping in the Red Sea and Gulf of Aden. In recent weeks, Iran has carried out a number of missile strikes against targets in Syria, Iraq and Pakistan, which it claimed were linked to the Islamic State group, Israel and a Baloch separatist group separately. Tehran also accused Israel — of which the United States is a close ally — of carrying out an air strike in the Syrian capital, Damascus, which killed five senior members of Iran"s security forces. Two US Navy Seals who went missing during an operation to seize Iranian-made weapons — bound for Houthis in Yemen — were presumed dead, the US military said earlier this week. The incident took place on Jan. 11 when commandos were boarding a ship off the coast of Somalia. According to media reports, one was swept away and the second jumped in to save him. "We mourn the loss of our two Naval Special Warfare warriors, and we will forever honor their sacrifice and example," said the head of Central Command, Gen. Michael Erik Kurilla. The US Navy identified the two as 27-year-old Navy Special Warfare Operator 2nd Class Nathan Gage Ingram and 37-year-old Navy Special Warfare Operator 1st Class Christopher J Chambers. Dan Sullivan, a Republican Senator from Alaska, said on X, formerly Twitter, that Iranian-backed proxies "have crossed a red line". Other Republicans have criticized President Biden for not doing more to curb Iran"s attacks on US assets in the region. "Iran is blatantly questioning US strength and resolve, thanks to [Joe Biden"s] appeasement of the world"s largest sponsor of terrorism," said Florida Senator Rick Scott in a post on social media. "It must end," he said. Senator Tom Cotton of Arkansas said that "the only answer to these attacks must be devastating military retaliation against Iran"s terrorist forces, both in Iran and across the Middle East". US Secretary of Defense Lloyd Austin has said that he is "outraged and deeply saddened" by the deaths of three US service members and the wounding of several others in last night"s attack. He said the troops were deployed to a site in north-eastern Jordan near the Syria border to work on combating the Islamic State. "These brave Americans and their families are in my prayers, and the entire Department of Defense mourns their loss," Austin said. He blamed "Iran-backed militias" for the attack, and reiterated President Biden"s comments that the US would respond "at a time and place of our choosing". "The president and I will not tolerate attacks on American forces, and we will take all necessary actions to defend the United States, our troops and our interests," he said. — BBC